1. Field of the Invention
This invention relates to winches and, more particularly, to a winch for lifting and positioning rolling doors during the installation of the doors.
2. Description of the Prior Art
U.S. Pat. No. 1,685,144 (Austin) discloses a wall board lidder which includes a ratchet winch system for raising a platform on which wall board is disposed.
U.S. Pat. No. 1,754,873 (Blackwood) discloses a hoisting apparatus which includes a reversible electric motor and a screw shaft The apparatus includes a boom, and a cable on the boom is secured to a load. As the screw shaft is raised, the load is raised via the cable system. The cable is secured to the boom and extends downwardly and under a pulley on a fixed base, and back up to the boom and over pulleys to where it is fastened to the load. A reversible electric motor is used to raise and lower the screw shaft which in turn raises the boom and the load.
U.S. Pat. No. 1,861,191 (Russell) discloses a lift system which includes a cable wound about a drum and the drum is in turn secured to a gear which meshes with a worm gear. A shaft on the worm gear includes a crank for rotating the worm gear which in turn causes the cable drum to rotate for either reeling out the cable or reeling in the cable. The apparatus is disposed on a wheeled dolly. The apparatus is described as being a service truck truck for lifting refrigerators.
U.S. Pat. No. 2,671,638 (Allen) discloses telescoping members on a cable system for raising and lowering the telescoping members. The apparatus includes a base element to which are secured caster wheels for moving the apparatus.
U.S. Pat. No. 2,714,434 (Peterson) discloses a hoisting system for raising and lowering a platform. The apparatus includes a triangular support system, and a pair of generally parallel like elements of the triangle comprises a slide on which a platform moves.
U.S. Pat. No. 2,896,908 (Stone) discloses a telescoping mast hoisting apparatus which utilizes a chain drive.
U.S. Pat. No. 2,983,474 (Hanna) discloses another telescoping mast system which includes a triangular base and castor wheels secured to the base for moving the apparatus. A crank cable system is used for raising and lowering the telescoping members.
U.S. Pat. No. 3,272,286 (Leduc) discloses a hoist system having telescoping members disposed on a movable base. The telescoping members are raised and lowered by means of a screw jack rotated by a gearing system and a hand crank.
U.S. Pat. No. 3,891,184 (Fields) discloses a telescoping mast system which includes a movable base. Telescoping members are raised and lowered by a hand crank and a cable. The telescoping members include a fixed outer tube, a middle tube and an inner tube. A single cable is used to raise the two movable tubular members. The cable extend through pulleys on the middle tube and is secured to the inner tube. Accordingly, as the cable is shortened, both the inner tube and the middle tube move upwardly.
U.S. Pat. No. 4,508,316 (Millard) discloses a telescoping system utilizing a hand crank and a cable for lifting a pair of telescoping members. The telescoping members are disposed on a movable base and an outer fixed tube is secured to the base, while a pair of telescoping members nest within each other. The telescoping members include a middle member and an inner member, and a single cable is used to lift both telescoping members at the same time by means of a single cable. The single cable utilizes pulleys on the middle member and is secured to the upper portion of the inner member.
U.S. Pat. No. 5,078,364 (Harrell) discloses a lock system for locking a telescoping mast in a desired location. A single cable is used to raise the mast, and to raise a platform on which a load is disposed. The apparatus includes wheels for moving the apparatus to a desired location.